Rotary displacement machines

ABSTRACT

A rotary compressor, vacuum pump, or expansion engine. Two interengaging rotors rotate within bores in a casing structure. Each rotor has a hub and a tooth. Plates are located against the four inside end walls of the two casing bores. The four plates are angularly adjustable so as to vary both the capacity and the internal pressure ratio. The machine has zero (or near zero) clearance volume so that (when operating as a compressor) substantially all of the compressed gas is delivered to the discharge ports.

[ 51 Mar. 27, 1973 blik ABSTRACT A rotary compressor, vacuum pump, or expansion engine. Two interengaging rotors rotate within bores in a casing structure. Each rotor has a hub and a tooth. airist the four inside end walls of The four plates are angularly adstable so as to vary both the capacity and the interhine has zero (or near zero) clearance volume so that (when operating as a FOREIGN PATENTS OR APPLICATIONS 492,024 9/1938 GreatBritain.......................

Primary Examiner-Carlton R. Croyle Assistant Examiner-John .1. Vra

Plates are located ag the two casing bores. ju nal pressure ratio. The mac Inventor: Arthur E. Brown, 117 East 5th St.,

Corning, N.Y. 14830 Nov. 23, 1970 Appl. No.: 91,987

US. Cl. ...................418/15, 418/159, 418/191 .F01c 21/12, F03c 3/00, F040 29/08 Field of Search.............418/15, 19, 30, 159, 191

References Cited UNITED STATES PATENTS 10/1970 Brownm.

Ernie $113 1&1 9-1 Brown 541 ROTARY DISPLACEMENT MACHINES 22 Filed:

[51] Int.C1........

d gas is 23 Claims, 10 Drawing Figures ..418/l91 .......418/15 compressor) substantially all of the compresse /2 delivered to the discharge ports.

Densham..

Schibbye..

Nilsson RathmarL.

PATENTEUMAR27 ms SHEET 1!]? 4 FIG. I]

PATENTEUHARZYISYS SHEET 3 OF 4 g x v,

I. &

ROTARY DISPLACEMENT MACHINES This application is related to U.S. Pat. Nos. 3,472,445 and 3,535,060.

DISCUSSION OF PRIOR ART Densham U.S. Pat. No. 2,580,006 varies internal pressure ratio but not capacity; and the flow rate is severely limited because of small end port area. This area would become even less if pressure ratios up to 3 were designed for. The Densham rotors have an axial thrust due to gas pressure. Densham does not use a true plate to control pressure ratio. Instead, Densham uses an opening 32 in a movable disk 31 which overlaps a fixed port 29. This does not provide optimum port location and results in a non-delivered clearance volume on the high pressure side of the machine. The Densham plates 31 and 32 would rub against the rotors as there is no axial holding means.

Rathman U.S. Pat. No. 2,656,972 varies internal pressure ratio but not capacity; and valve member 58 is not a true sector.

OBJECTS AND ADVANTAGES OF THIS INVENTION l. The principle object is to provide simple efficient means for varying capacity and/or internal pressure ratio in rotary machines of the class described. Internal pressure ratio is defined as the ratio of high pressure to low pressure inside the working chambers. Capacity has to do with volumetric flow rate.

2. Another object is to minimize the flow losses through the ports 25, particularly when the machine is rotors so as to obtain maximum flow area. (d) The special rotors shown in FIGS. VII and VIII reduce the flow loss at higher pressure ratios as will be explained.

3. Clearance volume in a rotary compressor is defined as a volumetric space into which gas is compressed but not delivered to the discharge line. The gas in such a clearance volume would be throttled back to inlet pressure resulting in a loss in both efficiency and capacity. Clearance volume is particularly undesirable in a higher pressure ratio machine where the weight of gas contained in a given clearance volume becomes a larger percentage of the delivered weight. Therefore, an object is to provide a'variable rotary machine such that the clearance volume is zero (or near zero). This objective is secured because: (a) True sector plates 27 (instead of overlapping plates) are used for varying pressure ratio; and (b) The rotors and ports are shaped such that clearance volume is zero (or near zero).

4. Another object is to pressure balance the rotors so as to reduce or eliminate axial thrust on the rotors due to gas pressure. This object is secured because the machine is symmetrical with a sector plate 27 located at each axial end of the machine.

5. Another object is to locate the sector plates 27 and the capacity control plates 42 directly in the main bores hub 7, a tooth 8, and two disks 9 bolted l0 and 3 and 4 of the casing structure. Thus it is not necessary to provide counterbores and the casing structure is thereby simplified.

6. Another object is to provide means to retain the plates 27 and 42 in axial position, yet, permit angular motion. Axial retention is necessary in order to prevent the plates from being forced (due to gas pressure) against the rotors.

7. Another object is to provide means for retaining the plates 27 and 42 in such a manner that the inward faces of the plates are free from slots or grooves. Such slots or grooves would result in clearance volume and added leakage.

8. Another object is to provide simple effective means for simultaneously moving each pair of plates 27 and 42. This objective is accomplished by means of a pinion and sector gear mechanism.

9. An advantage of the pinion and sector gear mechanism 36-39 is that there is a substantial gear reduction so as to overcome friction and provide for a smooth adjustment of the plates.

10. Another objective is to provide a lower cost arrangement (FIG. X) whereby one pair of control plates -60 is capable of varying capacity while maintaining internal pressure ratio approximately constant.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a section view taken midway along the axial length of the machine.

FIGS-II and .III are section views taken along the lines II-II and III-III in FIG. I.

FIGS. IV and V are section views taken along the lines IV-IV and V-V in FIG. III. In FIG. V, the plates 27 and 42 have been rotated through an angle from their positions shown in FIGS. I to IV.

FIG. VI is a larger scale section view of a portion of FIG. II. V

FIGS. VII and VIII are smaller scale views of modified rotors for use in the machine shown in FIGS. I

to VI.

FIGS. IX and X are section views of second and third embodiments of the invention.

Like numbers indicate similar parts throughout the drawings.

GENERAL DESCRIPTION AND OPERATION OF FIGS. ITO VI A first rotor l and a second rotor 2 are mounted for rotation in the intersecting bores 3 and 4 in the casing structure S and 6. The rotors are similar to those shown in U.S. Pat. No. 3,535,060. The first rotor 1 includes a dowelled 11 to the hub. A groove 12 passes in an axial direction through the hub and disks. The groove 12 is located adjacent to tooth 8 as shown in FIG. I. A cross section profile taken midway along the length of rotor 2 is referred to as the major cross section profile; and a profile taken at or near each end is referred to as the minor cross section profile.

The number 14 refers to the rotor tooth or lobe as seen in the major cross section profile. The number 16 refers to the rotor tooth or lobe as seen in the two minor cross section profiles. Tooth profiles 14 and 16 coincide outside the pitch circle H. The minor hubs 15 are smaller in diameter than the major hub 13. A groove 17 passes through the major hub.

When operating-as a compressor, a source of power is applied to the drive shaft 18 turning rotor 2 in the direction indicated. Timing gears 19 and 20 drive rotor 1 in timed relation. The rotor teeth 8 and 14 enter into and recede from the grooves 12 and l7as the rotors rotate. The hubs 7 and 13 rotate in sealing proximity to each other during a portion of each rotor cycle (as illustrated in FIG. I). The term sealing proximity also includes the case of rolling contact for hubs 7 and 13.

Gas (or the working fluid) enters the port 21 and fills main working chambers 22 and 23. When set for full capacity, internal compression begins when tip E reaches the bore juncture 24. A port 25 is located at each axial end of bore 3. The ports25 are covered over by the disks'9 during the compression and dwell portions of the rotor cycle so as to prevent backflow. After the gas in chambers 22 and 23 has been partially compressed, the disks 9 begin to uncover ports 25. The compressed gas is delivered through ports 25, and is then conducted through passages 26 to a manifold (not shown).

The passages 28 are for liquid coolant. Notches 32 provide more flow area as described in U.S. Pat. No. 3,535,060.

When operating as an expansion engine, the cycle is VARIABLE PRESSURE RATIO FIGS. ITO VI A sector plate 27 is located at each end of housing bore 3. A plate 34 is fastened to each plate 27 by means or rivets 29. A split retaining ring is fastened to the casing structure by means of studs 31. The retaining ring 30 has an overhanging edge 33 (FIGS. II AND VI) which engages plate 34 and thereby holds the sector plate assembly 27 in axial position against the end wall of the casing structure but permits angular motion. Each sector plate is centered with a lip 35 (FIG. III).

The clearance volume of the machine shown in FIGS. I to VI is zero (or near zero) even though the machine is arranged for variable pressure ratio. This features is made possible through the use of true sector plates 27 (instead of one port overlapping another for control of pressure ratio).

The terms sector plate and true sector plate are hereby defined as they apply to the description of the invention:'

In a true sector plate, the two radially directed edges of the plate extend to the outer periphery of the plate. A circular plate with an off center holetherein is not a true sector plate. The following definitions also apply.

In a true sector plate, one, radial edge of the plate forms one movable boundary of the port being controlled. The other radial boundary of the port remains fixed and lies in the same plane (perpendicular to the axes of the rotors) as said movable boundary. Referring to FIG. V, the edge (of true sector plate 27) forms one movable boundary of port 25. The other radial boundary 43 lies in the same plane as edge 40 but does not move relative to edge 40.

Pinion gears 36 and 37 (on shaft 38) mesh with sector gear teeth 39. The angular positions of the two sector plates 27 are thus simultaneously adjusted (during operation) by turning shaft 38.

Each sector plate 27 has two movable radially directed edges 40 and 41 (FIGS. I and V). The edge 40 (FIG. V) forms a movable partial boundary of higher pressure port 25 and thereby controls the point at Y which the working chambers come into open communication with port 25. The other movable radially directed edge 41 is not in communication with port 25; but instead is in communication with the lower pressure port 21.

The area of each port 25 varies according to the angular position of its sector plate 27. FIGS. I to IV illustrate the maximum pressure ratio setting. FIG. V illustrates a minimum pressure ratio setting.

In FIG. V, the outer edge of plate 42 forms a partial boundary of port 25 at 43. In FIG. V, the radially inward periphery of sector plate 27 is in the form ofa circular are 44 which is tangent to the outer radius 43 of plate 42.

In a non true sector plate, the plate overlaps a fixed port in the end wall of the housing and the change in port area is obtained by changing the amount ofsuch overlap. Nonof the applicants drawings show a non true sector plate for controlling internal pressure ratio.

VARIABLE CAPACITY FIGS. I TO vI A capacity control plate member 42 is located at. each end wall of the bore 4. The member 42 is retained in axial position by means of studs 31, split retaining rings 46, rivets 29, and smaller plates 45. The plate member's'42 can be angularly adjusted by means of sector gears 47 and pinion gears 48 (FIG. IV).

The angular position of edge 49 controls the point at which internal compression begins. FIG. V illustrates the maximum displacement position. FIGS. I to IV illustrate .a minimum displacement position. In FIG. I, compression-does not begin until the leading edge of toothl4 reaches the edge 49. Thus a portion of the working stroke is nullifiedsoas to reduce capacity. 1 Each end of the casing structure has a deep channel 50 so as to provide a passage for circulation of gas during i such 'nullifying phase of each cycle. One end of the channel 50 is shown at 51. If desired, the channel may be extended over to area 52 (FIG. I) so as to provide for additional circulation when ,set at reduced capacity. The channels 50 provide for axial inlet flow area in addition to the radial inlet 21.

FIG. VI is a larger scale view of a portion of FIG. II. A seal ring 53 seals the periphery of the plates.

THE FIG. I no'roas AR PARTICULARLY SUITED FOR use IN A VARIABLE CAPACITY MACHINE 4 capacity is reduced by nullifying part of the working displacement and not by reducing RPM.

The above discussion shown that flow losses due to reduced outlet port area (at reduced capacity and full pressure ratio) could become a problem. To minimize the above described port area problem, the applicant uses a set of rotors which have only one discharge stroke or phase per 360 rotor rotation. This means that the maximum angle occupied by the outlet ports 25 (and their area) can be much larger than if other type rotors (such as Densham) are used which have up to four discharge phases per rev.

The above discussion has shown that it is advantageous in a variable capacity machine to have only one discharge phase per 360 rotor rotation.

In comparing outlet port areas, it is necessary to take internal pressure ratio into account. A low pressure ratio compressor machine uses a discharge port with a large included angle. A high pressure ratio compressor machine requires'a port with a smaller included angle.

DISCUSSION OF FIGS. VII AND VIII These are reduced scale section views of modified rotors for use in the machine shown in FIGS. I to VI. These rotors are suited for higher pressure ratio; and they are identical to those shown in FIGS. XI and XII of U.S. Pat. No. 3,535,060. The FIG. VII and VIII rotors are particularly useful in a variable capacity machine as is explained as follows: The FIG. VII rotor permits the tooth 8 to advance farther before the disc 9' starts to uncover port 25. This permits the port 25 to have a larger area for a given pressure ratio. The desirable wide angle A is still retained. The purpose and advantages of a wide angle A are explained in U.S. Pat. No. 3,535,060. When operating as a compressor machine, the leading edge 68 of the disk lags behind the leading edge 69 of the groove in the rotor hub. When operating as an expansion engine, the trailing edge 69 of the groove in the rotor hub lags behind the trailing edge 68 in the disk. The two edges 68 and 69 are thus staggered.

DISCUSSION OF FIG. IX

This figure illustrates a method for varying capacity and/or internal pressure ratio in the machines described in US. Pat. No. 3,472,445. The FIG. IX section view is taken midway along the axial length of the machine; and the rotors and shafts have been omitted so as to illustrate the plates 54, 55, and 56 clearly.

DESCRIPTION OF FIG. X

This figure illustrates a lower cost method of varying capacity while maintaining internal pressure ratio approximately constant. The section view is taken midway along the axial length of the machine; and the rotors and shafts have been omitted. The rotors are generally similar to those shown in FIG. I. The filler plates 59 do not rotate and are fastened 61 to the easing. The sector plates 60 are movable and include a grillwork 62 of thin wall tubes brazed to one edge 66. The grillwork has the same axial thickness as the main body portion of sector plate 60. A deep channel 63 is located in each end wall of the casing structure. The channel 63 passes under sector plate 60 and ends at dotted line 64. To reduce capacity the sector plates 60 are rotated clockwise through a small angle. Minimum capacity would be reached when edge 63 reaches dotted line 64. I

When capacity is reduced (by nullifying a portion of the displacement as described) it is necessary to reduce the angle occupied by the discharge port in order to maintain constant internal pressure ratio; but the discharge port should be changed at a lesser rate .than the inlet port. The purpose of the grillwork 62 is to nullify a portion of the angular travel of sector plate 60 as far as pressure ratio is concerned. Thus, the effective angle of the discharge port does not start to reduce until edge 66 reaches fixed edge 67. This method does not give an exact control of internal pressure ratio at all settings but is close enough for many applications. This method of control is particularly suited for use with the machine shown in FIG. XIX of US. Pat. No. 3,535,060.

MODIFICATIONS NOT ILLUSTRATED Means for varying capacity and means for varying internal pressure ratio are both shown; but either means could be employed without the other.

The rotors as shown are non helical in form. Unlike screw type compressors, it is not necessary to make the rotors helical in order to secure internal compression. The rotors are generally simpler to construct if made with straight (non helical.) teeth and grooves. There are some conditions, however, where it is desirable to make the rotors helical.

The plates 27 and 42 could be reduced in outer radius and recessed into counterbores in the casing.

The two pinion gears 36 and 48 may be interconnected by means of gearing (not shown) such that internal pressure ratio is maintained constant while capacity is varied over a range.

An alternate means for axially retaining plates 27 and 42 is the use of magnets.

The sector plates 27 and capacity control plates 42 are shown flat on both sides. It would be possible to make both plates tapered or non flat on the faces away from the rotors. The term plate" in the claims shall include such a variation.

The drawings show the preferable plates 27 which are true sector plates. It would be possible to employ instead a movable disk (similar to Densham) which overlaps a fixed port. The term pressure control plate" (used in claims 5 and I0) is generic term which includes both the case of a disk overlapping a fixed port and the case of a true sector plate (as shown at 27).

The claims include the above modifications.

STATEMENTS PERTAINING TO THE CLAIMS by labeling a part by a different reference number or by omitting a number from a part.

As an aid, one or more claims contain underlining to indicate a point of novelty or an important component in a novel combination.

I claim: 1. In a rotary displacement machine adapted to bandie a working fluid, the combination of; a casing structure having a pair of intersecting bores, a first rotor mounted for rotation in one said bore, a second rotor mounted for rotation in the other said bore, each rotor having a hub and at least one working tooth, each said tooth projecting radially outward from its respective hub, each said tooth being adapted to rotate in sealing proximity to the wall of its respective casing bore, each hub having at least one groove therein, each groove being located radially inward from the outer radius of its respective hub, each groove being located in its respective hub at an angular location which is adjacent to a respective tooth, timing gear means constraining said two rotors to rotate in timed relation, each said tooth being adapted to enter into and recede from the groove in the opposite rotor hub as the rotors rotate, said two hubs being proportioned so as to rotate in sealing proximity to each other during a portion of each rotor cycle, said two rotors cooperating with each other and the casing structure to provide working chambers which displace the working fluid as the rotors rotate,

said casing structure having at least two ports for passage of the working fluid into and out of said working chambers, one of said ports being for passage of higher pressure working fluid and this port is therefore referred to asan H. P.'port, the other said port being for passage of lower pressure working fluid and this port is therefore referred to as an L. P. port, said H. P. port being located at an end of the bore containing said first rotor, said first rotor serving to cover said H. P. port during a .portion of each rotor cycle, said first rotor serving to uncover said H. P. port during another portion of each rotor cycle, said first rotor thus serving to control the flow of the working fluid through said H. P. port,

wherein the improvement comprises, a sector plate located at an end of the bore containing said first rotor, said sector plate being movable to various angular positions relative to the casing structure, said sector plate having two radially directed edges (40 and 41) which form partial boundaries of a cut-out portion of the sector plate, said two radially directed edges extending radially outward to the outer periphery of the sector plate, one said edge (40) forming a movable partial boundary of said H. P. port, the second said radially directed edge (41) being isolated from and sealed from said H. P. port, said second edge (41) being in communication with the working fluid at a pressure substantially lower than that contained in said H. P. port, and said sector plate serving to vary the angle of opening of said H. P. port so as to control the internal pressure ratio of said machine. 2. A rotary displacement machine as defined in claim i wherein: a said H. P. port is located at each end of the bore containing said first rotor, said first rotor controls the flow of the working fluid through both of said H. P. ports, a said sector plate is located at each end of the bore containing said first rotor, each sector plate is movable to various angular positions relative to the easing structure, each sector plate has an edge which forms a movable partial boundary of its respective H. P. port, each sector plate serves to vary the angle of opening of its respective H. P. port so as to control the internal pressure ratio of said machine, and the advantages of using two sector plates and two H. P. ports (instead of one of each) are: (a) there is more flow area and hence there is less flow loss through the H. P. ports and (b) the net axial pressure force on the first rotor is less hence there is less thrust load on the first rotor.

3. A rotary displacement machine as defined in claim 1 wherein: a capacity control plate member is located at an axial end of the borecontaining said second rotor, said capacity control plate member has an opening therein for passage of the working fluid, said capacity control plate member is movable to various angular positions relative to the casing structure, said capacity control plate member nullifies variable portions of the displacement of said rotors when moved to said various angular positions, and said capacity control plate member thereby serves to control the capacity of said machine.

. 4. A rotary displacement machine as defined in claim 1 wherein; a split ring memberis fastened to an end wall of the casing bore containing said first rotor, said split ring member has an overhanging edge which engages a said sector plate and thereby retains the sector plate in axial position inside the casing structure, and said ring member permits angular motion of the sector plate relative to the casing structure.

5. A rotary displacement machine as defined in claim 1 wherein; a said sector plate has a working outer radius less than the outer radius of said first rotor, a said H. P. port has an outer radius less than the outer radius of said first rotor, and a said H. P. port is controlled by the hub of the first rotor.

6. A rotary displacement machine asdefined in claim 1 wherein; a said sector plate has two radially directed edges, one said radially directed edge forms the movable partial boundary of a said H. P. port, the other said radially directed edge forms'the movable partial boundary of a said L. P. port, and said sector platethus serves dual functions which are: (a) the sector plate controls internal pressure ratio and (b) the same sector plate also controls the capacity of said machine.

7. A rotary displacement machine as defined in claim 6 wherein: grillwork is fastened to said edge (of the sector plate) which controls internal pressure ratio, and the purpose of said grillwork is to maintain a more constant internal pressure ratio while varying the capacity of said machine.

8. ln arotary displacement machine adapted to handie a working fluid, the combination of; a casing structure having a pair of intersecting bores, a first rotor mounted for. rotation in one said .bore, a'second rotormounted for rotation in the other said bore, each rotor having a hub and at least one working tooth, each said tooth projecting radially outward from its respective hub, each said tooth being adapted to rotate in sealing proximity to the wall of its respective bore, each hub having a groove therein, each said groove being located radially inward from the outer radius of its respective hub, each said groove being located in its respectivehub at an angular location which is adjacent to a respective tooth, timing gear means constraining said two rotors to rotate in timed relation at equal rotative speed, each said tooth being adapted to enter into and recede from the groove in the opposite rotor hub as the rotors rotate, said two hubs being proportioned so as to rotate in sealing proximity to each other during a portion of each rotor cycle, said two rotors cooperating with each other and the casing structure to provide working chambers which displace the working fluid as the rotors rotate,

said casing structure having at least three ports for passage of the working fluid into and out of said working chambers, two of said ports being for passage of higher pressure working fluid and these two ports are therefore referred to as'H. P. ports, the third said port being for passage of lower pressure working fluid and this port is therefore referred to as an L. P. port, said two H. P. ports being located one at each axial end of the bore containing said first rotor, said first rotor serving to cover both of said H. P. ports during a portion of each rotor cycle, said first rotor serving to uncover both of said H. P. ports during another portion of each rotor cycle, said first rotor thus serving to control the flow of the working fluid through both of said H. P. ports, wherein the improvement comprises, a sector plate located at each axial end of the bore containing said first rotor, each sector plate being movable to various angular positions relative to the casing structure, each sector plate having a radially directed edge which forms a movable partial boundary of a respective H. P. port, each sector plate serving to vary the angle of opening of a respective H. P. port so as to control the internal pressure ratio of said machine, an advantage of employing an H. P. port and a sector plate at each end of the first rotor bore (instead of at just one end) being a larger flow area, the number of working teeth contained by each rotor being equal to one, said machine (when operating as a compressor) having one discharge phase per rotor rotation, said machine (when operating as an expander) having one power phase per rotor rotation, and an advantage of using only one tooth per rotor (instead of more than one tooth) being to obtain a larger flow area through said H. P. ports for a given internal pressure ratio. 9. A rotary displacement machine as defined in claim 8 wherein; a capacity control plate member is located at an axial end of the bore containing said second rotor, said capacity control plate member has an opening therein for passage of the working fluid, said capacity control plate member is movable to various angular positions relative to the casing structure, said capacity control plate member serves to nullify variable portions of the displacement of said rotors when moved to said capacity control plate members (instead of one) is that there is more flow area for passage of the working fluid through said openings therein.

11. In a rotary displacement machine adapted to handle a working fluid, the combination of; a casing structure having a pair of intersecting bores, a first rotor mounted for rotation in one said bore, a second rotor mounted for rotation in the other said bore, each rotor having a hub and at least one working tooth, each said tooth projecting radially outward from its respective hub, each said tooth being adapted to rotate in sealing proximity to the wall of its respective casing bore, each hub having at least one groove therein, each said groove being located radially inward from the outer radius of its respective hub, each groove being located in its respective hub at an angular location which is adjacent to a respective tooth, timing gear means constraining said two rotors to rotate in timed relation, each said tooth being adapted to enter into and recede from the groove in the opposite rotor hub as the'rotors rotate, said two hubs being proportioned so as to rotate in sealing proximity to each other during a portion of each rotor cycle, said two rotors cooperating with each other and the casing structure to provide working chambers which displace the working fluid as the rotors rotate, said casing structure having at least three ports for passage of the working fluid into and out of said working chambers, two of said ports being for passage of higher pressure working fluid and these two ports are therefore referred to as H. P. ports, the third said port being for passage of lower pressure working fluid and this port is therefore referred to as an L. P. port, said two H. P. ports being located one at each end of the bore containing said first rotor,

the radially outward portion of each said H. P. port being located (from the axis of the first rotor) at a radial distance which is larger than the outer radius of said first rotor hub, said first rotor having a disk attached to each axial end, each said disk having an outer radius larger than the outer radius of said first rotor hub, each said disk having an opening passing in an axial direction through the disk, each said disk serving to control the flow of the working fluid through a respective H. P. port, wherein the improvement comprises,

a pressure control plate located at each end of the bore containing said first rotor, each pressure control plate being movableto various angular positions relative to the casing structure, each pressure control plate serving to vary the angle of opening of a respective H. P. port so as to control the internal pressure ratio of said machine, an advantage of employing an H. P. port and a pressurecontrol plate at each end of the first rotor bore (instead of at just one end) being a larger flow area,

the number of working teeth contained by each rotor being equal to one, said machine (when operating as a compressor) having one discharge phase per rotor rotation, said machine (when operating as an expander) having one power phase per rotor rotation, and an advantage of using only one working tooth per rotor (instead or more than one tooth) being to obtain a larger flow area through said H. P. ports for a given internal pressure ratio.

12. A rotary displacement machine as defined in claim 11 wherein; a capacity control plate member is located at an axial end of the bore containing said second rotor, said capacity control plate member has an opening therein for passage of the working fluid, said capacity control plate member is movable to various angular positions relative to the casing structure, said capacity control plate member serves to nullify variable portions of the displacement of said rotors when moved to said various angular positions, and said capacity control plate member thereby serves to control the capacity of said machine.

13. A rotary displacement machine as defined in claim 12 wherein; the outer radius of each said disk is substantially equal to the outer radius of said first rotor tooth, the outer radius of each said pressure control plate is substantially equal to the outer radius of a said disk, and the outer radius of said capacity control plate member is substantially equal to the outer radius of said second rotor tooth.

14. A rotary displacement machine as defined in claim 11 wherein; each said pressure control plate is in the form of a sector plate, a radially directed edge of each sector plate forms the movable partial boundary of a respective H. P. port, and each H. P. port has a variable area which varies according to the angular position of its respective sector plate.

15. A rotary displacement machine as defined in claim 14 wherein; a capacity control plate member is located at an axial end of the bore containing said second rotor, said capacity control plate member has an opening therein for passage of the working fluid, said capacity control plate member is movable to various angular positions relative to the casing structure, said capacity control plate member serves to nullify variable portions of the displacement of said rotors when moved to said various angular positions, and said capacity control plate member thereby serves to control the capacity of said machine.

16. In a rotary displacement machine adapted to handle a working fluid, the combination of; a casing structure having a pair of intersecting bores, a first rotor mounted for rotation in one said bore, a second rotor mounted for rotation in the other said bore, each rotor having a hub and at least one working tooth, each said tooth projecting radially outward from its respective hub, each said tooth being adapted to rotate in sealing proximity to the wall of its respective casing bore, each hub having at least one groove therein, each groove being located radially inward from the outer radius of its respective hub, each groove being located in its respective hub at an angular location which is adjacent to a respective tooth, timing gear means constraining said two rotors to rotate in timed relation,

each said tooth being adapted to enter into and recede rotate, said two hubs being proportioned so as to rotate in sealing proximity to each other during a portion of each rotor cycle, said two rotors cooperating with each other and the casing structure to provide working,

chambers which displace the working fluid as the rotors rotate,

said casing structure having at least three ports for passageof the working fluid into and out of said working chambers, two of said ports being for passage of higher pressure working fluid and these ports are therefore referred to as an H. P. ports, the other said port being for passage of lower pressure working fluid and this port is therefore referred to as a L. P. port, said H. P. ports being located one at each end of the bore containing said first rotor, said first rotor serving to cover said H.

P. ports during a portion of each rotor cycle, said first rotor serving to uncover said H. P. ports during another portion of each rotor cycle, said first rotor thus serving to control the flow of the working fluid through said H. P. ports,

wherein the improvement comprises, a pressure control plate located at each end of the bore containing saidfirst rotor, said pressure control plates 'being movable to various angular positions relative to the casing structure, said pressure control plates serving to vary the angle of opening of said H. P. ports so as to control the internal pressure ratio of said machine,

a capacity control plate member located at an axial end of the bore containing said second rotor, said capacity control plate member having an opening therein for passage of the working fluid, said capacity control plate member being movable to various angular positions relative to the casing structure, said capacity control plate member serving to nullify variable portions of the displacement of said rotors when moved to saidvarious angular positions, and said capacity control plate member thereby serving to control the capacity of said machine.

17. A rotary displacement machine as defined in claim 16 wherein; the number of working teeth contained by each rotor is equal to one, said machine when operating as a compressor has one discharge phase during each 360 rotation of the rotors, said machine when operating as an expander has one power phase during each 360 rotation of the rotors, and an advantage of using a single tooth per rotor (instead of more than one tooth) is to obtain a larger flow area through a said H. P. port for a given internal pressure ratio.

18. A rotary displacement machine as defined in claim 16 wherein; the radially outward portion of a said H. P. port is located (from the axis of the first rotor) at a radial distance which is larger than the outer radius of said first rotor hub, said first rotor has a disk attached to at least one axial end, said disk has an outer radius larger than the outer radius of said first rotor hub, said disk has an opening passing in an axial direction through the disk, said disk serves to cover a said H. P. port during a portion of each rotor cycle, said opening in the-disk serves to uncover a said H. P. port during another portion of each rotor cycle, said disk thus serves to control the flow of the working fluid through a said H. P. port,

said opening in the disk is in staggered relation with said groove in the first rotor hub, said staggered relation is such that the leading edge of said opening in the disk lags behind a leading edge of the groove when operating as a compressor machine, a trailing edge of said groove in the first rotor hub lags behind the trailing edge of said opening in the disk when operating as an expansion engine, the purpose of placing an edge of said groove in the rotor hub in staggered relation with an edge of the opening in the disk (as specified in this claim) is to delay the time of opening of said H. P. port when operating as a compressor machine and to advance the time of closing of said H. P. port when operating as an expansion engine, and said delayed opening and advanced closing of the H. P. port increases the internal pressure ratio of said machine.

19. A rotary displacement machine as defined in claim 16 wherein; an outer peripheral edge of a said capacity control plate member forms the partial boundary of a said H. P. port, a said sector plate has a radially inward portion of its periphery in the form of a circular arc (the profile of which is designated are 44), and the outer periphery of said capacity control plate member is tangent to said are 44.

20. .A rotary displacement machine as defined in claim 16 wherein; the radially outward portion of each said H. P. port is located (from theaxis of the first rotor) at a radial distance which is larger than the outer radius of said first rotor hub, said first rotor has a disk attached to at least one axial end, said disk has an outer radius larger than the outer radius of said first rotor hub, said disk has an opening passing in an axial direction through the disk, said disk serves to cover a said H. P. port during a portion of each rotor cycle, said opening in the disk serves to uncover a said H. P. port during another portion of each rotor cycle, and said disk thus serves to control the flow of the working fluid through a said H. P. port.

21. A rotary displacement machine as defined in claim 20 wherein; an edge of said groove in the hub of the first rotor is staggered along its axial length the purpose of which is to delay thetime of opening of a said H. P. port when operating as a compressor machine and to advance the time of closing of said H. P. port when operating as an expansion engine, and said delayed opening and advanced closing of the H. P. port increases the internal pressure ratio of said machine.

22. A rotary displacement machine as defined in claim 16 wherein; a ring member is fastened to the end wall of the casing bore containing said second rotor, said ring member has an overhanging edge which engages a said capacity control plate member and thereby retains the control plate member in axial position inside the casing structure, and said ring member permits angular motion of the capacity control plate member relative to the casing structure.

23. The combination defined in claim 22 wherein; said ring member is fastened to the casing end wall with pin like fasteners, said capacity control plate member is a composite structure comprised of multiple plates fastened together, and a purpose of making the capacity control plate member in the form of an assembled composite structure 18 to permit assembly of said ring member into said capacity control plate member. 

1. In a rotary displacement machine adapted to handle a working fluid, the combination of; a casing structure having a pair of intersecting bores, a first rotor mounted for rotation in one said bore, a second rotor mounted for rotation in the other said bore, each rotor having a hub and at least one working tooth, each said tooth projecting radially outward from its respective hub, each said tooth being adapted to rotate in sealing proximity to the wall of its respective casing bore, each hub having at least one groove therein, each groove being located radially inward from the outer radius of its respective hub, each groove being located in its respective hub at an angular location which is adjacent to a respective tooth, timing gear means constraining said two rotors to rotate in timed relation, each said tooth being adapted to enter into and recede from the groove in the opposite rotor hub as the rotors rotate, said two hubs being proportioned so as to rotate in sealing proximity to each other during a portion of each rotor cycle, said two rotors cooperating with each other and the casing structure to provide working chambers which displace the working fluid as the rotors rotate, said casing structure having at least two ports for passage of the working fluid into and out of said working chambers, one of said ports being for passage of higher pressure working fluid and this port is therefore referred to as an H. P. port, the other said port being for passage of lower pressure working fluid and this port is therefore referred to as an L. P. port, said H. P. port being located at an end of the bore containing said first rotor, said first rotor serving to cover said H. P. port during a portion of each rotor cycle, said first rotor serving to uncover said H. P. port during another portion of each rotor cycle, said first rotor thus serving to control the flow of the working fluid through said H. P. port, wherein the improvement comprises, a sector plate located at an end of the bore containing said first rotor, said sector plate being movable to various angular positions relative to the casing structure, said sector plate having two radially directed edges (40 and 41) which form partial boundaries of a cut-out portion of the sector plate, said two radially directed edges extending radially outward to the outer periphery of the sector plate, one said edge (40) forming a movable partial boundary of said H. P. port, the second said radially directed edge (41) being isolated from and sealed from said H. P. port, said second edge (41) being in communication with the working fluid at a pressure substantially lower than that contained in said H. P. port, and said sector plate serving to vary the angle of opening of said H. P. port so as to control the internal pressure ratio of said machine.
 2. A rotary displacement machine as defined in claiM i wherein: a said H. P. port is located at each end of the bore containing said first rotor, said first rotor controls the flow of the working fluid through both of said H. P. ports, a said sector plate is located at each end of the bore containing said first rotor, each sector plate is movable to various angular positions relative to the casing structure, each sector plate has an edge which forms a movable partial boundary of its respective H. P. port, each sector plate serves to vary the angle of opening of its respective H. P. port so as to control the internal pressure ratio of said machine, and the advantages of using two sector plates and two H. P. ports (instead of one of each) are: (a) there is more flow area and hence there is less flow loss through the H. P. ports and (b) the net axial pressure force on the first rotor is less hence there is less thrust load on the first rotor.
 3. A rotary displacement machine as defined in claim 1 wherein: a capacity control plate member is located at an axial end of the bore containing said second rotor, said capacity control plate member has an opening therein for passage of the working fluid, said capacity control plate member is movable to various angular positions relative to the casing structure, said capacity control plate member nullifies variable portions of the displacement of said rotors when moved to said various angular positions, and said capacity control plate member thereby serves to control the capacity of said machine.
 4. A rotary displacement machine as defined in claim 1 wherein; a split ring member is fastened to an end wall of the casing bore containing said first rotor, said split ring member has an overhanging edge which engages a said sector plate and thereby retains the sector plate in axial position inside the casing structure, and said ring member permits angular motion of the sector plate relative to the casing structure.
 5. A rotary displacement machine as defined in claim 1 wherein; a said sector plate has a working outer radius less than the outer radius of said first rotor, a said H. P. port has an outer radius less than the outer radius of said first rotor, and a said H. P. port is controlled by the hub of the first rotor.
 6. A rotary displacement machine as defined in claim 1 wherein; a said sector plate has two radially directed edges, one said radially directed edge forms the movable partial boundary of a said H. P. port, the other said radially directed edge forms the movable partial boundary of a said L. P. port, and said sector plate thus serves dual functions which are: (a) the sector plate controls internal pressure ratio and (b) the same sector plate also controls the capacity of said machine.
 7. A rotary displacement machine as defined in claim 6 wherein: grillwork is fastened to said edge (of the sector plate) which controls internal pressure ratio, and the purpose of said grillwork is to maintain a more constant internal pressure ratio while varying the capacity of said machine.
 8. In a rotary displacement machine adapted to handle a working fluid, the combination of; a casing structure having a pair of intersecting bores, a first rotor mounted for rotation in one said bore, a second rotor mounted for rotation in the other said bore, each rotor having a hub and at least one working tooth, each said tooth projecting radially outward from its respective hub, each said tooth being adapted to rotate in sealing proximity to the wall of its respective bore, each hub having a groove therein, each said groove being located radially inward from the outer radius of its respective hub, each said groove being located in its respective hub at an angular location which is adjacent to a respective tooth, timing gear means constraining said two rotors to rotate in timed relation at equal rotative speed, each said tooth being adapted to enter into and recede from the groove in the opposite rotor hub as the rotors rotate, said two hubs being propoRtioned so as to rotate in sealing proximity to each other during a portion of each rotor cycle, said two rotors cooperating with each other and the casing structure to provide working chambers which displace the working fluid as the rotors rotate, said casing structure having at least three ports for passage of the working fluid into and out of said working chambers, two of said ports being for passage of higher pressure working fluid and these two ports are therefore referred to as H. P. ports, the third said port being for passage of lower pressure working fluid and this port is therefore referred to as an L. P. port, said two H. P. ports being located one at each axial end of the bore containing said first rotor, said first rotor serving to cover both of said H. P. ports during a portion of each rotor cycle, said first rotor serving to uncover both of said H. P. ports during another portion of each rotor cycle, said first rotor thus serving to control the flow of the working fluid through both of said H. P. ports, wherein the improvement comprises, a sector plate located at each axial end of the bore containing said first rotor, each sector plate being movable to various angular positions relative to the casing structure, each sector plate having a radially directed edge which forms a movable partial boundary of a respective H. P. port, each sector plate serving to vary the angle of opening of a respective H. P. port so as to control the internal pressure ratio of said machine, an advantage of employing an H. P. port and a sector plate at each end of the first rotor bore (instead of at just one end) being a larger flow area, the number of working teeth contained by each rotor being equal to one, said machine (when operating as a compressor) having one discharge phase per rotor rotation, said machine (when operating as an expander) having one power phase per rotor rotation, and an advantage of using only one tooth per rotor (instead of more than one tooth) being to obtain a larger flow area through said H. P. ports for a given internal pressure ratio.
 9. A rotary displacement machine as defined in claim 8 wherein; a capacity control plate member is located at an axial end of the bore containing said second rotor, said capacity control plate member has an opening therein for passage of the working fluid, said capacity control plate member is movable to various angular positions relative to the casing structure, said capacity control plate member serves to nullify variable portions of the displacement of said rotors when moved to said various angular positions, and said capacity control plate member thereby serves to control the capacity of said machine.
 10. A rotary displacement machine as defined in claim 9 wherein; a capacity control plate member is located at both axial ends of the bore containing said second rotor, both of said capacity control plate members (with openings therein) serve to nullify variable portions of the displacement of said rotors when moved to various angular positions, both of said capacity control plate members thereby serve to control the capacity of said machine, and an advantage of using two capacity control plate members (instead of one) is that there is more flow area for passage of the working fluid through said openings therein.
 11. In a rotary displacement machine adapted to handle a working fluid, the combination of; a casing structure having a pair of intersecting bores, a first rotor mounted for rotation in one said bore, a second rotor mounted for rotation in the other said bore, each rotor having a hub and at least one working tooth, each said tooth projecting radially outward from its respective hub, each said tooth being adapted to rotate in sealing proximity to the wall of its respective casing bore, each hub having at least one groove therein, each said groove being located radially inward from the outer radius of its respective hub, each groove being located in its respective hub at an angulaR location which is adjacent to a respective tooth, timing gear means constraining said two rotors to rotate in timed relation, each said tooth being adapted to enter into and recede from the groove in the opposite rotor hub as the rotors rotate, said two hubs being proportioned so as to rotate in sealing proximity to each other during a portion of each rotor cycle, said two rotors cooperating with each other and the casing structure to provide working chambers which displace the working fluid as the rotors rotate, said casing structure having at least three ports for passage of the working fluid into and out of said working chambers, two of said ports being for passage of higher pressure working fluid and these two ports are therefore referred to as H. P. ports, the third said port being for passage of lower pressure working fluid and this port is therefore referred to as an L. P. port, said two H. P. ports being located one at each end of the bore containing said first rotor, the radially outward portion of each said H. P. port being located (from the axis of the first rotor) at a radial distance which is larger than the outer radius of said first rotor hub, said first rotor having a disk attached to each axial end, each said disk having an outer radius larger than the outer radius of said first rotor hub, each said disk having an opening passing in an axial direction through the disk, each said disk serving to control the flow of the working fluid through a respective H. P. port, wherein the improvement comprises, a pressure control plate located at each end of the bore containing said first rotor, each pressure control plate being movable to various angular positions relative to the casing structure, each pressure control plate serving to vary the angle of opening of a respective H. P. port so as to control the internal pressure ratio of said machine, an advantage of employing an H. P. port and a pressure control plate at each end of the first rotor bore (instead of at just one end) being a larger flow area, the number of working teeth contained by each rotor being equal to one, said machine (when operating as a compressor) having one discharge phase per rotor rotation, said machine (when operating as an expander) having one power phase per rotor rotation, and an advantage of using only one working tooth per rotor (instead or more than one tooth) being to obtain a larger flow area through said H. P. ports for a given internal pressure ratio.
 12. A rotary displacement machine as defined in claim 11 wherein; a capacity control plate member is located at an axial end of the bore containing said second rotor, said capacity control plate member has an opening therein for passage of the working fluid, said capacity control plate member is movable to various angular positions relative to the casing structure, said capacity control plate member serves to nullify variable portions of the displacement of said rotors when moved to said various angular positions, and said capacity control plate member thereby serves to control the capacity of said machine.
 13. A rotary displacement machine as defined in claim 12 wherein; the outer radius of each said disk is substantially equal to the outer radius of said first rotor tooth, the outer radius of each said pressure control plate is substantially equal to the outer radius of a said disk, and the outer radius of said capacity control plate member is substantially equal to the outer radius of said second rotor tooth.
 14. A rotary displacement machine as defined in claim 11 wherein; each said pressure control plate is in the form of a sector plate, a radially directed edge of each sector plate forms the movable partial boundary of a respective H. P. port, and each H. P. port has a variable area which varies according to the angular position of its respective sector plate.
 15. A rotary displacement machine as defined in claim 14 wherein; a capacity control plate member is located at an axial eNd of the bore containing said second rotor, said capacity control plate member has an opening therein for passage of the working fluid, said capacity control plate member is movable to various angular positions relative to the casing structure, said capacity control plate member serves to nullify variable portions of the displacement of said rotors when moved to said various angular positions, and said capacity control plate member thereby serves to control the capacity of said machine.
 16. In a rotary displacement machine adapted to handle a working fluid, the combination of; a casing structure having a pair of intersecting bores, a first rotor mounted for rotation in one said bore, a second rotor mounted for rotation in the other said bore, each rotor having a hub and at least one working tooth, each said tooth projecting radially outward from its respective hub, each said tooth being adapted to rotate in sealing proximity to the wall of its respective casing bore, each hub having at least one groove therein, each groove being located radially inward from the outer radius of its respective hub, each groove being located in its respective hub at an angular location which is adjacent to a respective tooth, timing gear means constraining said two rotors to rotate in timed relation, each said tooth being adapted to enter into and recede from the groove in the opposite rotor hub as the rotors rotate, said two hubs being proportioned so as to rotate in sealing proximity to each other during a portion of each rotor cycle, said two rotors cooperating with each other and the casing structure to provide working chambers which displace the working fluid as the rotors rotate, said casing structure having at least three ports for passage of the working fluid into and out of said working chambers, two of said ports being for passage of higher pressure working fluid and these ports are therefore referred to as an H. P. ports, the other said port being for passage of lower pressure working fluid and this port is therefore referred to as a L. P. port, said H. P. ports being located one at each end of the bore containing said first rotor, said first rotor serving to cover said H. P. ports during a portion of each rotor cycle, said first rotor serving to uncover said H. P. ports during another portion of each rotor cycle, said first rotor thus serving to control the flow of the working fluid through said H. P. ports, wherein the improvement comprises, a pressure control plate located at each end of the bore containing said first rotor, said pressure control plates being movable to various angular positions relative to the casing structure, said pressure control plates serving to vary the angle of opening of said H. P. ports so as to control the internal pressure ratio of said machine, a capacity control plate member located at an axial end of the bore containing said second rotor, said capacity control plate member having an opening therein for passage of the working fluid, said capacity control plate member being movable to various angular positions relative to the casing structure, said capacity control plate member serving to nullify variable portions of the displacement of said rotors when moved to said various angular positions, and said capacity control plate member thereby serving to control the capacity of said machine.
 17. A rotary displacement machine as defined in claim 16 wherein; the number of working teeth contained by each rotor is equal to one, said machine when operating as a compressor has one discharge phase during each 360* rotation of the rotors, said machine when operating as an expander has one power phase during each 360* rotation of the rotors, and an advantage of using a single tooth per rotor (instead of more than one tooth) is to obtain a larger flow area through a said H. P. port for a given internal pressure ratio.
 18. A rotary displacement machine as defined in claim 16 wherein; the radially outward portion of a said H. P. port is located (from the axis of the first rotor) at a radial distance which is larger than the outer radius of said first rotor hub, said first rotor has a disk attached to at least one axial end, said disk has an outer radius larger than the outer radius of said first rotor hub, said disk has an opening passing in an axial direction through the disk, said disk serves to cover a said H. P. port during a portion of each rotor cycle, said opening in the disk serves to uncover a said H. P. port during another portion of each rotor cycle, said disk thus serves to control the flow of the working fluid through a said H. P. port, said opening in the disk is in staggered relation with said groove in the first rotor hub, said staggered relation is such that the leading edge of said opening in the disk lags behind a leading edge of the groove when operating as a compressor machine, a trailing edge of said groove in the first rotor hub lags behind the trailing edge of said opening in the disk when operating as an expansion engine, the purpose of placing an edge of said groove in the rotor hub in staggered relation with an edge of the opening in the disk (as specified in this claim) is to delay the time of opening of said H. P. port when operating as a compressor machine and to advance the time of closing of said H. P. port when operating as an expansion engine, and said delayed opening and advanced closing of the H. P. port increases the internal pressure ratio of said machine.
 19. A rotary displacement machine as defined in claim 16 wherein; an outer peripheral edge of a said capacity control plate member forms the partial boundary of a said H. P. port, a said sector plate has a radially inward portion of its periphery in the form of a circular arc (the profile of which is designated arc 44), and the outer periphery of said capacity control plate member is tangent to said arc
 44. 20. A rotary displacement machine as defined in claim 16 wherein; the radially outward portion of each said H. P. port is located (from the axis of the first rotor) at a radial distance which is larger than the outer radius of said first rotor hub, said first rotor has a disk attached to at least one axial end, said disk has an outer radius larger than the outer radius of said first rotor hub, said disk has an opening passing in an axial direction through the disk, said disk serves to cover a said H. P. port during a portion of each rotor cycle, said opening in the disk serves to uncover a said H. P. port during another portion of each rotor cycle, and said disk thus serves to control the flow of the working fluid through a said H. P. port.
 21. A rotary displacement machine as defined in claim 20 wherein; an edge of said groove in the hub of the first rotor is staggered along its axial length the purpose of which is to delay the time of opening of a said H. P. port when operating as a compressor machine and to advance the time of closing of said H. P. port when operating as an expansion engine, and said delayed opening and advanced closing of the H. P. port increases the internal pressure ratio of said machine.
 22. A rotary displacement machine as defined in claim 16 wherein; a ring member is fastened to the end wall of the casing bore containing said second rotor, said ring member has an overhanging edge which engages a said capacity control plate member and thereby retains the control plate member in axial position inside the casing structure, and said ring member permits angular motion of the capacity control plate member relative to the casing structure.
 23. The combination defined in claim 22 wherein; said ring member is fastened to the casing end wall with pin like fasteners, said capacity control plate member is a composite structure comprised of multiple plates fastened together, and a purpose of making the capacity control plate member in the form of an assembled composite structure is to permit assembly of said ring member into saId capacity control plate member. 